1. Field of Invention
This invention relates to a device for locating a distant object and communicating its position to another person, or more particularly a device which permits one person to locate a celestial object and to illustrate its position to another person.
2. Discussion of the Prior Art
For centuries people have viewed the heavens at night and sought to point out stars, planets and other astronomical objects to others. The process, though, can be most difficult. There are thousands of objects in the night sky and most are just points of light which, except for subtle differences in color, are identical. The night sky lacks any accessible coordinate system, eliminating any possibility of readily describing an object in terms of its declination or right ascension, as longitude and latitude in the night sky are conventionally described. Objects like stars are distributed at random, the constellations they form only identifiable to the trained eye and even that with some imagination. For these reasons, describing the location of an object in the night sky can be most frustrating, especially when teaching children.
Star charts have been used for decades as an aid to locating objects. These charts consist of a map of the sky. By looking at the chart, and then the sky, usually several times, the viewer can gradually become accustomed to patterns in the stars and will be able to locate one object relative to another. One viewer, wishing to point out an object to another, can point it out on the star chart. The second viewer can then locate it in the sky by locating the object among the pattern of the stars.
The method described above is most readily suited to experienced observers. Novice observers have difficulty orienting themselves so they can relate the star chart to what they see in the sky. Further confusion is caused by the earth's rotation and its movement around the sun. This causes the applicable chart to change from night to night and hour to hour. Further, most charts, to be useful, must be oriented with respect to map coordinates and novices can have difficulty in locating the northern star, Polaris, an essential part of the process. In addition, such charts, to be read, must be lit, yet lighting can cause the eye to dilate, reducing visual sensitivity. Charts are subject to being blown around by the wind and soaking up moisture from sources such as dew. Finally, such charts, being flat, distort the position of the stars which appear to the observer as if they were arrayed on a celestial sphere.
Astronomers can make use of sophisticated instruments based on the coordinate system consisting of declination and right ascension. This permits an astronomer to locate objects and to communicate their position with precision. However, few outside the community of professions and serious amateur observers can master the complex system or work the tools necessary to utilize it, tools which include clock driven motors in most cases. Such tools are not generally available to casual observers, can be expensive, and are not easily understood by children.
The ultimate tool for locating objects are computerized, motor driven telescopes, which are now available to the general public. With a touch of a few buttons, the telescope swings to a position which permits any given star, planet, cluster or other astronomical object to be viewed in the eye piece. However, these telescopes are expensive, delicate and sometimes heavy. They can be difficult to set up, especially with regard to polar and right ascension alignment. Children, and some adults, have difficulty viewing through eye pieces, which, in any case, restrict the field of view.
Most recently, the use of lasers as pointing devices has been proposed. These lasers are pointed toward the object in the sky to be illustrated. The other viewers look up in the sky and see the laser beam extending toward the object. However, the relatively high power laser beams usable for such purposes can be unsafe for use by the untrained or around children. The high power needed to sustain the laser requires power supplies with large energy capacities which limits the usefulness of batteries, makes the lasers heavy and may limit such devices to the range that can be achieved with a power cord. Such high power lasers are not readily accessible to the general public, and when available are expensive. Further, the beam itself is not visible. The system works by reflecting the laser beam off dust in the atmosphere. Such dust is not always present in sufficient quantity to yield a usable display of the laser beam. Indeed, the best times for viewing are the nights when the sky is relatively free of dust and at these times the laser beam system may not function well. Further, the light of some laser beams may alter the night visual sensitivity of some viewers.
Atamian (U.S. Pat. No. 4,970,793, Nov. 20, 1990) describes a method for locating celestial objects utilizing a transparent hollow globe with phosphorescent indicia to indicate the location of stars. The method requires the following steps. First a "sun position table" is consulted to locate the position of the sun in the sky relative to the background of stars. Then a removable "sun sticker" is applied to the globe at that location. The globe is then rotated to align its horizon with the latitude of the observer's horizon. A second chart or reference source may be needed to identify the observer's latitude. A knob is then turned to align a horizontally positioned ring with the "sun sticker". These steps being completed, the globe is then illuminated with light to make the indicia glow. For a few moments, the indicia will be visible. For those moments, a single observer may align, through juxtaposition, the globe with the night sky to identify objects.
The method proposed by Atamian is complex. It involves two reference charts and careful alignment of the apparatus using the data obtained from two charts. Further, to function, it requires bright light which can reduce the viewer's night vision. Further, the globe can only be used by one observer at a time. Only one observer is aligned so that juxtaposition can be achieved. A second observer, viewing the same indicia at the same time will not be aligned due to the effect of parallax.